Puberty clues An international team of researchers have identified 30 genes connected to the onset of periods in women, some of which regulate body weight and fat metabolism.

Last year a similar series of studies identified a group of genetic variants associated with body mass index (BMI) and the onset of menarche.

This new review of 32 studies includes more than 87,000 women from Europe, US and Australia, and triples the number of puberty genes identified.

Puberty in women normally occurs between 11 and 14 years of age. According to researchers the onset of puberty, known as menarche, is partly triggered when a child reaches a certain weight - around 45 kilograms.

Study co-author, Dr Enda Byrne of the Queensland Institute of Medical Research says the results from this study show that many of the genes that increase risk for weight gain and obesity in adulthood, also influence the onset of puberty.

"This supports the idea that the body launches into puberty once it reaches a certain level of nutrient stores and therefore children who are overweight are more likely to undergo early puberty," says Byrne.

Medical researchers are concerned that the earlier puberty starts, the greater the risk of health problems, such as breast cancer, type 2 diabetes, cardiovascular disease, as well as shorter adult stature.

Byrne says while genes play a role in the timing of menarche, diet and lifestyle are also responsible.

"There has been a gradual decrease in the average age of menarche in the population over the last century which has been attributed to improved child nutrition," he says.

"Some women inherit genes that make them more susceptible to weight gain and early puberty, but changes in lifestyle such as healthier eating and exercise can alter these genetic effects."

Complex range of processes

The study also found genes involved in hormone regulation, cell development and other mechanisms linked to the onset of puberty.

The researchers say this shows the onset of puberty timing is controlled by a complex range of biological processes.

They believe similar genetic factors may influence the onset of puberty in boys.

"One of the next stages of this study will be to test whether the same genes also influence timing of puberty in males," says Byrne.

The study was supported in Australia by the National Health and Medical Research Council and the Australian Research Council.